Tyrannosaurinae

Tyrannosaurinae is one of the two subfamilies of tyrannosaurid theropods, known from Late Cretaceous deposits of western North America and east Asia. Compared with their albertosaurine relatives, tyrannosaurines were generally more robust, larger, and more heavily built, with deep, powerful skulls; the exceptions were the long-snouted, more gracile alioramins. The group includes some of the oldest tyrannosaurids, such as Lythronax, alongside its youngest and most famous member, Tyrannosaurus rex. Its genera are usually sorted into several lineages: the basal Alioramini, the American southwestern Teratophoneini, and a group uniting the Daspletosaurini and the Tyrannosaurini, which contains Tarbosaurus and Tyrannosaurus. Studies of Tyrannosaurus growth suggest these animals changed markedly with age, shifting from slender, semi-long-snouted juveniles into robust, heavy-headed adults that likely occupied different ecological niches as they matured.